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I bought an '87 B2 several days ago. It had not been driven much in a good while. But it start and run though. I drained the little bit of fuel left in the tank today and added fresh fuel with some Seafoam. Started the engine, got it up to oper temp. Then turned off and pulled the codes. Got a 21 and 51. Both have to do with engine temp sensor (I think).

But when I tried starting the truck back up after pulling the codes it wouldnt start. it'd just turn over. finally I pushed the accelerator and it finally started. But the idle is much higher as it runs. I killed it and tried pulling codes again. But this time the truck will not kick in to the test mode. I cannot pull codes now for some reason. I tried disconnecting the battery and trying again. But it will not start now unless I floor the accelerator. And then it idles much faster than normal I(just under 1500 rpms.

I'm wondering if something happened to the Engine Control computer or some other component. Anybody have an idea?

Check your throttle positon sensor. See if there is an even resistance as you open and close the throttle body. MAybe check connections at the computer or PCM. If you have a manual it will tell you how to test TP Sen. Yeah i think it has something to do with the throttle body. the computer gets a certain voltage from the TP sensor to tell the computer how much air is going in so the computer can think "hey there is air going in i can start to spit this amount of gas in" So it can run at the right fuel mixture. then when you start it does it run rough. ok how does it react when you stomp the gas. if it hesitates. probably will. because it is only running off what the O2 sensor in the pipe tells the computer to do. If you do the test on the TP sensor and it checks out it could allso be a bad wire or a wire that is not even connected.

Alright tell me what happens.